Gasmaster GMI 2M, Installation, Operation And Maintenance Manual

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IOM GMI 2M & 2ML Nov 2010.doc
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3.1.4 Main Flame
I:
Once pilot flame is established burner controller will send 120V to the two main
safety shut off valves. From these valves gas flows into the gas butterfly valve (see
schematic diagram on page 9 of the Riello catalogue).
II:
Air supplied by the blower flows through to the burner head where it mixes with
gas and the air/gas mixture is ignited by the flame rod.
III:
The pilot safety shut of valves will close five seconds after the main safety valves
are opened. If at any time during the operation flame (pilot or main) is not detected
the boiler/water heater will immediately shut down and will not restart until the
burner controller is manually reset.
3.1.5
Operation
The unit continues to operate at low fire for as long as the outlet (discharge)
temperature remains higher than the desired temperature- with respect to the
differentials -, and lower than the maximum operating temperature; both being set
on the temperature controller. The temperature sensor installed on the outlet
manifold continuously measures the discharge water temperature. Signals from this
sensor are sent to the temperature controller. If the temperature measured by the
sensor is below that of the desired temperature, corresponding signals are sent to
the servomotor. This will open the gas butterfly valve and air damper
proportionately, thereby increasing the input capacity of the unit to its maximum
value at high fire. As soon as the discharge water reaches the desired temperature
(set on the controller by the owner), the process is reversed and the input is
decreased so that discharge water remains at constant temperature. This throttle
(load tracking) process continuously takes place through increase or decrease in the
air/gas mixture (opening/closing of the butterfly valve and air damper), thereby
ensuring water is always supplied at
±
1
°
C of the desired operating (discharge)
temperature.
If the outlet water temperature reaches the maximum operating temperature, the
boiler/water heater will shut down and goes into the stand by mode. The unit will
automatically re-start when the water temperature drops below the operating set
point minus the differential temperature.